[PATCH] LoongArch: Make align symbol be in same section with alignment directive

[Xi Ruoyao]

On Sat, 2024-01-06 at 15:23 +0800, Jinyang He wrote:
> R_LARCH_ALIGN (psABI v2.30) requires a symbol index. The symbol is only
> created at the first time to handle alignment directive. This means that
> all other sections may use this symbol. If the section of this symbol is
> discarded, there may be problems. Search it in its own section.
> 
> gas/ChangeLog:
> 
> 	* config/tc-loongarch.c: (get_align_symbol) New function.
> 	* gas/testsuite/gas/loongarch/relax_align2.d: New test.
> 	* gas/testsuite/gas/loongarch/relax_align2.s: Likewise.
> 
> Reported-by: WANG Xuerui <git@xen0n.name>
> Link: https://lore.kernel.org/loongarch/2abbb633-a10e-71cc-a5e1-4d9e39074066@loongson.cn/T/#t

Hmm, but shouldn't we avoid using R_LARCH_ALIGN in the first place if -
mno-relax?

> ---
>  gas/config/tc-loongarch.c                  | 53 ++++++++++++++++++++--
>  gas/testsuite/gas/loongarch/relax_align2.d | 24 ++++++++++
>  gas/testsuite/gas/loongarch/relax_align2.s | 11 +++++
>  3 files changed, 84 insertions(+), 4 deletions(-)
>  create mode 100644 gas/testsuite/gas/loongarch/relax_align2.d
>  create mode 100644 gas/testsuite/gas/loongarch/relax_align2.s
> 
> diff --git a/gas/config/tc-loongarch.c b/gas/config/tc-loongarch.c
> index 5348371fa2c..29e540df429 100644
> --- a/gas/config/tc-loongarch.c
> +++ b/gas/config/tc-loongarch.c
> @@ -392,6 +392,50 @@ loongarch_target_format ()
>    return LARCH_opts.ase_lp64 ? "elf64-loongarch" : "elf32-loongarch";
>  }
>  
> +typedef struct
> +{
> +  segT sec;
> +  symbolS *s;
> +} align_sec_sym;
> +
> +static htab_t align_hash;
> +
> +static hashval_t
> +align_sec_sym_hash (const void *entry)
> +{
> +  const align_sec_sym *e = entry;
> +  return (hashval_t) e->sec;
> +}
> +
> +static int
> +align_sec_sym_eq (const void *entry1, const void *entry2)
> +{
> +  const align_sec_sym *e1 = entry1, *e2 = entry2;
> +  return e1->sec == e2->sec;
> +}
> +
> +static symbolS *get_align_symbol(segT sec)
> +{
> +  align_sec_sym search = { sec, NULL };
> +  align_sec_sym *pentry = htab_find (align_hash, &search);
> +  if (pentry)
> +    return pentry->s;
> +
> +  /* If we not find the symbol in this section. Create and insert it. */
> +  symbolS *s = (symbolS *)local_symbol_make (".Lla-relax-align", sec,
> +					     &zero_address_frag, 0);
> +  align_sec_sym entry = { sec, s };
> +  align_sec_sym **slot =
> +      (align_sec_sym **) htab_find_slot (align_hash, &entry, INSERT);
> +  if (slot == NULL)
> +    return NULL;
> +  *slot = (align_sec_sym *) xmalloc (sizeof (align_sec_sym));
> +  if (*slot == NULL)
> +    return NULL;
> +  **slot = entry;
> +  return entry.s;
> +}
> +
>  void
>  md_begin ()
>  {
> @@ -413,6 +457,8 @@ md_begin ()
>  		    it->name, it->format, it->macro);
>        }
>  
> +  align_hash = htab_create (10, align_sec_sym_hash, align_sec_sym_eq, free);
> +
>    /* FIXME: expressionS use 'offsetT' as constant,
>     * we want this is 64-bit type.  */
>    assert (8 <= sizeof (offsetT));
> @@ -1721,10 +1767,9 @@ loongarch_frag_align_code (int n, int max)
>  
>    nops = frag_more (worst_case_bytes);
>  
> -  s = symbol_find (".Lla-relax-align");
> -  if (s == NULL)
> -    s = (symbolS *)local_symbol_make (".Lla-relax-align", now_seg,
> -				      &zero_address_frag, 0);
> +  s = get_align_symbol(now_seg);
> +  if (!s)
> +    as_fatal (_("internal error: cannot get align symbol"));
>  
>    ex.X_add_symbol = s;
>    ex.X_op = O_symbol;
> diff --git a/gas/testsuite/gas/loongarch/relax_align2.d b/gas/testsuite/gas/loongarch/relax_align2.d
> new file mode 100644
> index 00000000000..d647d9b7eef
> --- /dev/null
> +++ b/gas/testsuite/gas/loongarch/relax_align2.d
> @@ -0,0 +1,24 @@
> +#as: --no-warn
> +#readelf: -rsW
> +#skip: loongarch32-*-*
> +
> +Relocation section '\.rela\.text' at offset .* contains 2 entries:
> +.*
> +0+04[ 	]+0000000500000066[ 	]+R_LARCH_ALIGN[ 	]+0+[ 	]+\.Lla-relax-align \+ 4
> +0+14[ 	]+0000000500000066[ 	]+R_LARCH_ALIGN[ 	]+0+[ 	]+\.Lla-relax-align \+ 404
> +
> +Relocation section '\.rela\.text2' at offset .* contains 2 entries:
> +.*
> +0+04[ 	]+0000000600000066[ 	]+R_LARCH_ALIGN[ 	]+0+[ 	]+\.Lla-relax-align \+ 4
> +0+14[ 	]+0000000600000066[ 	]+R_LARCH_ALIGN[ 	]+0+[ 	]+\.Lla-relax-align \+ 404
> +
> +Symbol table '\.symtab' contains .* entries:
> +#...
> +[ 	]+.*:[ 	]+0+[ 	]+0[ 	]+SECTION[ 	]+LOCAL[ 	]+DEFAULT[ 	]+1[ 	]+\.text
> +#...
> +[ 	]+.*:[ 	]+0+[ 	]+0[ 	]+SECTION[ 	]+LOCAL[ 	]+DEFAULT[ 	]+5[ 	]+\.text2
> +#...
> +[ 	]+.*:[ 	]+0+[ 	]+0[ 	]+NOTYPE[ 	]+LOCAL[ 	]+DEFAULT[ 	]+1[ 	]+\.Lla-relax-align
> +#...
> +[ 	]+.*:[ 	]+0+[ 	]+0[ 	]+NOTYPE[ 	]+LOCAL[ 	]+DEFAULT[ 	]+5[ 	]+\.Lla-relax-align
> +#pass
> diff --git a/gas/testsuite/gas/loongarch/relax_align2.s b/gas/testsuite/gas/loongarch/relax_align2.s
> new file mode 100644
> index 00000000000..6cd6bd8731b
> --- /dev/null
> +++ b/gas/testsuite/gas/loongarch/relax_align2.s
> @@ -0,0 +1,11 @@
> +.section ".text", "ax"
> +nop
> +.align 4
> +nop
> +.align 4, , 4
> +
> +.section ".text2", "ax"
> +nop
> +.align 4
> +nop
> +.align 4, , 4

-- 
Xi Ruoyao <xry111@xry111.site>
School of Aerospace Science and Technology, Xidian University